Technical advances in various fields in recent years have been accompanied by increasing demand for heat resistant materials that can be used in high temperature environments, and for lightweight and high-strength materials. In a case of conventional ceramic fibers, with regard to the fibers containing silica added for improving elastic modulus of them at normal temperature, where these are used in high temperature environments, a glass phase forms in the grain boundary area of them, which serves as a starting point for fracture, with the result that high strength of them is not achieved. Systems employing oxides exclusively have the drawback that once they are placed beyond a certain temperature environments, rapid particle growth and particle deformation occur in the systems, resulting a sharp decline in their strength. (References: T. F. Cooke, J. Am. Ceram. Soc., 74 (12) 2959-78 (1991), W. R. Cannon and T. R. Langdon, J. Mat. Sci., 18 (1983), and so on)
With the foregoing in view, it is an object of the present invention to provide a fiber having reduced matrix particle deformation in high temperature environments which can be used as a heat resistant material, and a method for the manufacture thereof.